Conventionally there are three-dimensional action adventure type games that are set in busy downtown streets and in which the user's character moves through the streets while talking and fighting with the people present there as the story advances. In these types of games, effort is made to depict the busy downtown streets by displaying on the game screen a large number of passersby who do not contribute to the progress of the game.
However, if detailed control is to be carried out in these games for each passerby individually using AI (artificial intelligence) or the like, there is a problem that a very large load is placed on the CPU (central processing unit) of the game device and sufficient processing for drawing may not be possible in practical use.
Restricting the number of passersby that appear on the game screen is conceivable as a technique for solving this problem (for example, see Japanese patent application JP H10-165647A). However, in this case, merely restricting the number of passersby that appear on a single game screen reduces the quality of the game graphically.
Accordingly, it is conceivable that if very detailed control could be achieved even when restricting the number of passersby appearing on the game screen by not uniformly restricting the number of passersby throughout all scenes of the game screen but rather not restricting the number of passersby in certain portions of the game screen and restricting the number of passersby in certain other portions, then very detailed scene control could be achieved while preventing any reduction in the quality of the game.
However, in previously disclosed methods, it is not possible to restrict the number of passersby that appear on the game screen for each portion of the game screen.
Furthermore, with conventional games, there is a problem in that memory resources continue to be maintained for objects (people and things) that have left the game screen in order to manage those objects after they have left the game screen regardless of whether or not there is a necessity to manage their positions and movements, and moreover there is a problem of wasteful cases in which several codes are being executed (memory resources being used even though nothing is shown on the game screen).